Recently, due to the high petroleum price and the unstable nature of the oil supply, there is a strong incentive to produce fuels and chemical products from renewable feedstocks. Development and marketing of biodiesel and bioethanol fuels are in high gear. Bio-diesel fuel made from plant oils and bio-ethanol made from corn or sugar plants are already in the market and are expected to grow at fast rates. To support this growth, a large amount of well-priced natural oils and ethanol are expected to become available. These natural oils have chemical compositions unsuitable for high performance product application.
Natural oils, especially plant oils, are unsuitable for high performance synthetic lubricant base stock application or polymer plasticizers, such as plasticized or flexible polyvinyl chloride (PVC) products. This is because natural oils contain high amounts of triglycerides of unsaturated fatty acids. The high amount of unsaturation and the high amount of long chain fatty acids contribute to the poor oxidative stability, poor low temperature properties and poor plasticization properties. Heretofore known, synthetic lubricant base stocks or plasticizers have excellent performance. However, they are all derived from non-renewable petroleum feedstock.
Triglycerides are the major component in naturally occurring fats and oils. A triglyceride is the condensation product of one molecule of glycerol with three molecules of fatty acids to yield three molecules of water and one molecule of triglyceride. A fatty acid is an aliphatic compound containing 4 to 24 carbon atoms and having a terminal carboxyl radical. Naturally occurring fatty acids, with only some exceptions, have an even number of carbon atoms and, if any unsaturation is present, the first double bond is generally located between the ninth and tenth carbon atoms. The characteristics of the triglycerides are strongly influenced by the nature of their fatty acid radicals. For a detailed description of triglycerides refer to U.S. Pat. No. 4,545,941, incorporated herein by reference.
Alpha-olefins are primarily used as intermediates in the production of polyolefins, chemicals, and consumer products. For example, 1-propene is used to make polypropylene, acrylonitrile, propylene oxide, and isopropyl alcohol. The major uses of 1-butene are to produce poly(1-butene) and various four carbon aldehydes and alcohols. The higher alpha-olefins and internal olefins are commonly used in the manufacture of synthetic lubricating oils, detergents, plasticizer alcohols, flavors, perfumes, dyes, pharmaceuticals, and resins. The major commercial source of alpha-olefins is petroleum. Alpha-olefins and internal olefins can be produced through a cross-metathesis reaction of renewable feedstocks with an alkene, such as ethylene, in the presence of a metathesis catalyst.
U.S. Pat. No. 4,545,941, discloses production of certain alpha-olefins by reacting triglycerides having fatty acid esters containing isolated carbon-carbon double bonds with ethylene at an ethylene partial pressure of about 200-550 psig in the presence of a metathesis catalyst, specifically a catalyst comprising a tungsten compound and a tin compound (e.g. tungsten hexachloride tetramethyl tin). The reaction is carried out at a temperature of 100° F. to 500° F.
Ahmad et al., Co-Metathesis Reaction of Crude Palm Oil and Ethene, Journal of the American Oil Chemists' Society Pub. No. 72(6), 757-8 (1995), discloses the co-metathesis reaction of crude palm oil with ethene in the presence of tungsten hexachloride and tetramethyl tin WCl6Me4Sn, followed by termination of this reaction with methanol, which gives terminal alkenes. The major metathesis products are 1-decene and Me 9-decenoate.
The first successful metathesis conversion in the field of unsaturated fatty acid esters and oils was performed in 1972 by Boelhouwer and coworkers, viz., the selective transformation of methyl oleate (methyl cis-9-octadecenoate), a readily available unsaturated ester, into equimolar amounts of 9-octadecene and dimethyl 9-octadecene-1,18-dioate, in the presence of the catalyst system WCl6/(CH3)4Sn. Catalytic metathesis of unsaturated fatty acid esters and oils is described in J. C. Mol, Catalytic Metathesis of Unsaturated Fatty Acid Esters and Oils, Topics in Catalysts Vol. 27, Nos. 1-4 (February 2004), which is incorporated herein by reference.
U.S. Patent Publication No. 2007/0179307 discloses a process for co-producing an olefinic fraction and a composition of diacids or diesters of fats. The process comprises, in succession: a) metathesis of an unsaturated fat with ethylene in the presence of a metathesis catalyst and at least one non-aqueous ionic liquid; b) separating and recycling the ionic liquid used in the first step; c) separating, by distillation, the olefinic fraction (fraction A) from the unsaturated fat mono-ester or mono-basic acid fraction (fraction B) formed in step a); d) homometathesis of the mono-unsaturated fat ester or acid cut (fraction B) which allows the co-production of unsaturated fat diesters or diacids (fraction C) and ethylene which is recycled to the first methathesis step of the process; and e) optionally, recycling the ionic liquid containing the catalyst used in step d). Particularly preferred starting material is an oleic sunflower seed oil, an oleic rapeseed oil or mono-alcohol esters of said oils, whereupon the process can produce both an olefinic fraction (mainly composed of 1-decene) and a composition of diesters or diacids wherein, in general, over half of the chains is constituted by unsaturated C18 chains (mainly composed of octadecene-9 1,18-diacid or diester). The ethylene employed is recycled to the first methathesis step.
Poly alpha-olefins (PAOs) comprise a class of hydrocarbons manufactured by the catalytic oligomerization (polymerization to low-molecular-weight products) of linear alpha-olefin (LAO) monomers. LAOs typically range from 1-octene to 1-dodecene, with 1-decene being a preferred material, although oligomeric copolymers of lower olefins such as ethylene and propylene may also be used, including copolymers of ethylene with higher olefins as described in U.S. Pat. No. 4,956,122 and the patents referred to therein.
Some PAO products have achieved importance in the lubricating oil market. Specifically, PAOs may be produced by the polymerization of olefin feed in the presence of a catalyst such as AlCl3, BF3, or promoted AlCl3, BF3, or metallocene catalyst systems promoted by a non-coordinating anion or methylaluminoxane. PAOs of different viscosity grades are typically produced using promoted BF3 or AlCl3 catalysts. Processes for the production of PAOs are disclosed, for example, in the following patents: U.S. Pat. Nos. 3,997,621; 6,949,688; 3,833,678; 6,410,812; 3,997,621; 6,949,688; 3,149,178; 3,382,291; 3,742,082; 3,780,128; 4,172,855; 4,956,122; WO 2007/111,776; and WO 2007/011,462, which are incorporated by reference.
Several publications propose polymerization of various alpha-olefins, at least some in the presence of metallocene catalyst systems, to provide polymers having various utilities, such as lubricant components. For example, WO 2007/011462 discusses a process for producing PAOs of high viscosity index (HVI-PAOs), including contacting a feed comprising a mixture of LAOs with an activated metallocene catalyst to produce liquid polymers for use in lubricant components or as functional fluids. The copolymer composition may be made from at least two different alpha-olefins of C3 to C30 range, with monomers randomly distributed in the polymers. In an embodiment, one of the monomers is a higher alpha-olefin, such as one chosen from C12 to C18 alpha-olefins, and the second one or more alpha-olefin is, e.g., chosen from C3 to C7 alpha-olefins. In another embodiment there are used propylene or 1-butene as one of the feed components, as they are readily available from refinery or petrochemical plants. The resulting copolymers are said to have useful lubricant properties, including excellent VI, pour point, low temperature viscometrics by themselves or as a blend fluid with other lubricants or polymers.
Efforts have been made to prepare various PAOs using metallocene catalyst systems. Examples include U.S. Pat. No. 6,706,828, which discusses production of PAOs in the presence of meso-forms of certain metallocene catalysts under high hydrogen pressure with methyl alumoxane as an activator. WO 02/14384 and WO 99/67347 discuss similar topics.
U.S. Pat. No. 5,859,159 is directed to a dilute process for the polymerization of non-ethylene, alpha-olefin homopolymers and copolymers in the presence of metallocene catalyst systems. The alpha-olefin feed stream used in the process comprises at least one alpha-olefin, such as propylene, 1-butene, pentene-1,4-methyl-pentene-1, hexene-1, octene-1 and higher alpha-olefins up to and including nanodecene-1, e.g., mixtures of propylene and butene-1. The polymers of most of the examples have isotactic index of at least 80%. The product can be used as a backbone for production of lubricants, or oil dispersants and viscosity modifiers.
Plasticizers are incorporated into resins to increase the flexibility, workability, or distensibility of the resins. The largest use of plasticizers is in the production of plasticized or flexible PVC products. Typical uses of plasticized PVC products include films, sheets, tubing, coated fabrics, wire and cable insulation and jacketing, adhesives, sealants, inks, and medical products, such as blood bags and tubing, and similar articles. Other polymer systems that use small amounts of plasticizers include polyvinyl butyral, acrylic polymers, nylon, polyolefins, polyurethanes, and certain fluoroplastics. A listing of the major plasticizers and their compatibilities with different polymer systems is provided in “Plasticizers,” A. D. Godwin, in Applied Polymer Science 21st Century, edited by C. D. Craver and C. E. Carraher, Elsevier (2000); pp. 157-175.
Natural triglycerides from various vegetable oils have been tried as plasticizers in the past but have compatibility issues. The alkyl groups on these natural triglycerides are linear, and the alkyl chain is too long to have good compatibility. Soybean oil has been epoxidized (ESO) to try to improve its compatibility and performance as a plasticizer. Even with the polarity of the epoxide group, ESO has long term compatibility issues due to the long alkyl chains (C16-C18). It is generally used as a PVC stabilizer rather than a plasticizer. Stabilizers are used at much lower concentrations than plasticizers.